Hemolytic Uremic Syndrome

For 24 hours, a 62-year-old woman had had severe weakness, abdominal pain, and watery diarrhea that had become bloody in the past 12 hours. She had no significant medical history. The patient was confused and dehydrated. Tenderness was noted in the right lower quadrant. Temperature was 37.2°C (99°F); heart rate, 110 beats per minute; and blood pressure, 90/50 mm Hg. Her white blood cell count was 15,000/μL; platelet count, 60,000/μL; hemoglobin, 9 g/dL; hematocrit, 32%; blood urea nitrogen level, 85 mg/dL; serum creatinine, 2.1 mg/dL; and fibrinogen, 95 mg/dL. D-dimer levels were increased.

A peripheral blood smear revealed schistocytes, fragmented and deformed erythrocytes, and thrombocytopenia (A). Colonoscopy findings showed friable, inflamed, and hemorrhagic mucosa (B). A stool culture was positive for Escherichia coli, serotype 0157:H7. Lucia C. Fry, MD, and Klaus E. Mönkemüller, MD, of Chandler, Ariz, diagnosed enterohemorrhagic colitis with hemolytic uremic syndrome. This syndrome is characterized by acute hemolytic anemia, renal failure with uremia, and disseminated intravascular coagulation. It occurs in patients with enterohemorrhagic E coli or shigellosis intestinal infection.¹

Outbreaks of bloody colitis secondary to infection with the specific serotype of E coli 0157:H7 have been linked to inadequately cooked ground-beef hamburgers at fast-food restaurants.² Most subsequent outbreaks have been associated with ingestion of contaminated food or milk, but person-to-person transmission can also occur.³ Children younger than 5 years and elderly persons are particularly susceptible to this syndrome.³ The pathophysiology primarily involves toxin-induced damage (caused by Shiga-like toxins), which produces endothelial alterations and thrombosis that finally results in intestinal ischemia. There is no evidence that early antimicrobial therapy for enteric infection prevents hemolytic uremic syndrome.

Treatment consists of hemodialysis and supportive care. Because this syndrome is usually self-limited, antibiotics are not recommended. This patient received supportive therapy with intravenous fluids and electrolyte replacement. During the next 24 hours, her condition improved markedly and she did not require plasmapheresis or hemodialysis.